The present invention relates to a mounting assembly for a non-contact tool and, more particularly, to a breakaway assembly by which such a tool may be displaced from its mounting without damage as a result of encountering an obstacle in its operating path.
Non-contact tools, such as oxyfuel or plasma cutting torches, are used in a variety of applications where the tool is mounted to a carriage for movement relative to but spaced from a workpiece to be operated upon. In particular, oxyfuel or plasma cutting torches are used to cut a variety of sizes and shapes from steel plate. The plate is generally supported on a work table and the cutting torch or a bank of cutting torches is supported by an overhead carriage for programmed cutting movement over the steel plate workpiece.
As the cutting torch or torches move over the surface of the plate being cut, cut or partially cut pieces and scraps often fail to fall completely to an underlying support on the cutting table and instead tilt upwardly resulting in so-called "tip-ups" which may lie directly in the path of and be struck by the tip of the torch. Although it is well known in the art to automatically control torch height and positioning relative to the workpiece to maintain a proper torch position, the automatic detection of tip-ups or other obstructions has not been successfully overcome. Therefore, occasional collisions between a torch and an obstruction is unavoidable and quite common. The usual result of a torch collision is either major misalignment of the torch or damage to the torch and/or carriage mechanism. Thus, in addition to requiring major realignment by qualified technicians, expensive repairs may also be required.
Continuing developments in two areas of the plate cutting art have compounded the problems of torch misalignment and damage resulting from collision obstructions. First of all, the continued development of plasma cutting systems has compounded the problem of manual control by the operator to detect and avoid collisions. Plasma systems cut much more rapidly than gas torches and, as a result, much less time is available for operator reaction to avoid collision with a tip-up, the side of the cutting table, or some other obstruction. In addition, the plasma cutting arc is typically shielded by a water muffler or by cutting under water, making the visual detection of tip-ups increasingly difficult if not impossible. Also, improvements in guidance and control systems have enhanced the accuracy of both oxyfuel and plasma cutting systems, but have consequently required much greater accuracy in realigning and repositioning torches which have collided with an obstruction.
There is, therefore, a need for a non-contact tool mounting system, such as may be used for oxyfuel or plasma cutting torches, which will allow the tool or torch to break away without damage when it encounters an obstruction and yet be easily repositioned and realigned for continued operation. Such a tool mounting system must be able to maintain a precision operating position during cutting, be easily displaced from the operating position if it encounters an obstruction, and be subsequently repositioned quickly and accurately in the same precision operating position. It would also be desirable to automatically provide the operator with a signal that a collision has occurred, or to temporarily interrupt or shutdown the cutting process.